from what ive read, all the campsites within the national park are first come first served. i have yet to camp this park but im headed there this weekend, tho not to camp. if you havent checked out the website, i would suggest it. as far as trout streams, definitely pick yourself up a regulations guide to find out which streams are in season and which are closed. i would imagine that around september 1st it shouldnt be too super crowded.